Kilyos comes from the Greek word Kilya meaning sand…
Kilyos, with saying/rumour that it comes from the word Kilya which means sand in Greek, also there is another widepread saying that it derived from the word Killa with original Kuwaila and meaning nice walkway/strait. Yet, the meanings of both words suit to the the geographical situation of Kilyos. Although the name of Kilyos was changed to Kumköy during the Republican era, the name Kilyos is still widely used today.
The settlement in Kilyos had began in ancient times. It had been popular as a small fishing village. Then it had improved during the Roman Empire. When the Roman Empire disintegrated, the region that joined into the Byzantine lands, had become an attractive place for the civilizations of the region dealing with maritime because of its geographical location. The Genoese had also dominated this region for a while.
After the turmoil in the region during the Crusades, Kilyos, which entered into Ottoman rule, became a cosmopolitan settlement center with the development of Levantine population. While it while it was a township bounded to the Çatalca district until 1930, it was included into the Sarıyer district with the administrative arrangement made at that time.
Kilyos has gained importance since the 1970s when it became difficult to enter into the sea from the coasts of the Bosphorus and Marmara Sea. Sea pollution in the Marmara and the Bosphorus and the beaches of the Marmara coasts begin to close one by one, lead to a new search for shores of Istanbul residents in the summer. Kilyos, preferred by those who prefer to swim and picnic only on weekends, has become a place of choice for all seasons for the pleasure of holiday and weekend with the opening of many motels and restaurants. It is famous for its long and pristine sand beaches.
The historical building that catches the eye first when you arrive the settlement is the castle known to be built during the Genoese period.
The castle within the military field had been restored during the time of Sultan II. Mahmut. A system was installed to collect water to fill the cisterns in the middle of the castle when it rained. At the date of 1197-1241, of hegira calendar, all the cisterns until Bahçeköy had undergone reconstruction and restoration in this period. The arched, sheltered and clean guard sections of the stonemade castle has been remarkably preserved. II. The steel ball with 19th century Krupp wedge given by the Germans in World War for the protection of the Straits is located in the bastions of the castle. On the gate of the castle where 8 different balls are displayed, there is Sultan II. Mahmut tughra, two battle balls on both sides, a monumental plane tree that was planted in that period and reached to the present day. In the signboard, the date of the planting of the plane tree, which is 26 meters high and has a body circumference of 5.4 meters, is specified as the year of 1460. The water levels at three high points are part of the system that distributes water from the cistern in the castle. Other historical buildings in the village are the old rescue buildings, boathouse, pier, bridge and fountains they used to control the entrance of the Bosphorus when the British invaded Istanbul. The rescuing buildings are still in use by the coast guard.